The use of electromagnetic measurements in prior art downhole applications, such as logging while drilling (LWD) and wireline logging applications is well known. Such techniques may be utilized to determine a subterranean formation resistivity, which, along with formation porosity measurements, is often used to indicate the presence of hydrocarbons in the formation. Moreover, azimuthally sensitive directional resistivity measurements are commonly employed e.g., in pay-zone steering applications, to provide information upon which steering decisions may be made, for example, including distance and direction to a remote bed. Directional resistivity tools often make use of tilted or transverse antennas (antennas that have a magnetic dipole that is tilted or transverse with respect to the tool axis).
One challenging aspect in utilizing directional electromagnetic resistivity measurements, such as acquired a model of PeriScope®, an LWD downhole tool available from Schlumberger Technology Corporation, Sugar Land, Tex., is obtaining a reliable measurement of the dip azimuth angle between the borehole and a remote bed boundary. Prior art methods (which are described in more detail below) for obtaining the dip azimuth angle can be both noisy and susceptible to phase wrapping issues. Therefore, there is a need in the art for a more robust method for obtaining the dip azimuth angle from electromagnetic measurements.